Lexical Definition

‎κεραία‎ keraía (ker-ah'-yah) tittle ^G:N-F
feminine of a presumed derivative of the base of ‎κέρας‎

tittle.

• something horn-like, i.e. (specially) the apex of a Hebrew letter (figuratively, the least particle)

Abbott-Smith

* κεραία (WH, κερέα, v. App., 151), -ας, ἡ (< κέρας),
a little horn: of the point or extremity which distinguishes some Heb. letters from others (e.g. ד from ר; DCG, ii, 733), Mt 5:18, Lk 16:17.†

Abbott-Smith References

Liddell-Scott-Jones

κεραία,

poetry κεν-αίη, ἡ, (κέρας) horn, [Refs 2nd c.BC+]

__2 antennae of the crayfish or of insects, [Refs 4th c.BC+]
__II anything projecting like a horn: hence,
__II.1 yard-arm, [Refs 5th c.BC+], etc.; κ. καθελέσθαι, ὑφιέναι, i.e.lower sail, [Refs 2nd c.BC+]
__II.1.b projecting beam of a crane, etc., [Refs 5th c.BC+]
__II.1.c projecting parts of the hucklebone, [Refs 4th c.BC+]
__II.1.d branching stake of wood, used as a pale in a palisade, [Refs 2nd c.BC+]
__II.1.e horns of the ancilia, [Refs 1st c.AD+]
__II.2 plural, horns of the moon, [Refs 4th c.BC+]
__II.3 in writing, apex of a letter, [NT+4th c.BC+]; διὰ πάσης κ. διῆκον showing itself in every word of a speech, [Refs 1st c.BC+]
__II.4 leg of a pair of compasses, [Refs 2nd c.AD+]
__II.5 projecting spur of a mountain, [Refs 1st c.AD+]; of the horns of Europe and Africa at the Straits of Gibraltar, [Refs 6th c.AD+]; arms of a harbour, [Refs 2nd c.AD+]
__II.6 ={κέρας} see [Refs], wing of an army, [Refs 3rd c.AD+]
__II.7 plural, supposed teat-like projections inside the womb, [Refs]; but the Fallopian tubes, [Refs 2nd c.AD+]
__III bow made of horn, [Refs 6th c.AD+]

_{LSJ Scripture Refs: Matt.5.18 ☩ Luke.16.17}